This invention relates to electrical apparatus for powering automatic self-developing camera equipment from a battery of limited capacity. More particularly, the invention provides electrical control apparatus which limits the charging of a photographic flash tube to selected operating conditions when other powered elements of the camera system are quiescent. The control apparatus also restricts exposure, and hence film consumption, to selected conditions of flash tube readiness.
It is known in the art to control the operating sequence of an automatic self-developing camera to enable a single battery of limited capacity to power the entire camera cycle. U.S. Pat. No. 3,846,812, for example, discloses equipment which operates a flash camera of the automatic self-developing type so that only one operation of significant current drain occurs at a time. The film transport motor and the flash unit accordingly draw battery current at different times.
The advent of automatic focusing for cameras imposes an additional operation of relatively high current drain on the camera battery. When this operation overlaps with another operation of significant current drain, the battery voltage is likely to drop to such a degree that the battery is incapable of properly operating the camera. The camera then malfunctions with loss of the picture in process and typically with significant user irritation. U.S. Pat. No. 3,522,764 discloses one automatic focusing camera, and pending applications Ser. No. 729,289 for "Automatic Focusing Camera" by E. Shenk and Ser. No. 729,392 for "Ultrasonic Ranging System for Camera", by J. Muggli disclose further systems for automatic camera focusing, which as used herein includes ranging.
The user moreover is not to be burdened with separate switches for each aspect of camera operation. For example, it would be unsatisfactory to have separate switches for the automatic focus operation, for the flash charging operation, and for transporting a film unit through the rollers which initiate the developmental processing of the film. Moreover, these and other operating steps are to be controlled in a manner that maximizes the likelihood of securing a "perfect" picture with each exposure. Thus, it is not satisfactory to allow the charge on the flash tube capacitor to degrade beyond a controlled limit before exposure, while the capacitor focuses and frames the camera, for the resultant illumination would be deficient and the picture would be underexposed.
Other prior art includes U.S. Pat. No. 4,001,639 which discloses camera equipment that inhibits the charging of a flash unit when the camera battery voltage is low. It is also known, for example from U.S. Pat. No. 4,064,519, to inhibit the operation of a camera when the flash tube capacitor has insufficient charge, or when all flash bulbs in an array are spent.
It is an object of this invention to provide an automatically-focusing self-developing flash camera which can be powered by a single battery. To this end, it is an object of the invention to provide a self-developing camera having automatic focusing, automatic exposure control, and automatic advance of exposed film, and which charges the flash tube capacitor only at times other than those operations. It is a further object of the invention to provide a camera control system for attaining the foregoing features in a manner which sequences the camera operations for high user convenience. In this regard, it will be appreciated that imposing the constraints of the battery system on the camera user would be unsatisfactory.
It is also an object of the invention to provide camera control equipment for providing the foregoing operation and which allows a film unit to be exposed only when the flash tube capacitor is properly charged.
It is another object of the invention to provide a control system of the above character for a single lens reflex camera in which the viewfinder is only in focus after the auto-focus operation.
Other objects of the invention will in part be obvious and will in part appear hereinafter.